1997 xj immobilizer issues

[Roler]

Originally Posted by carvesdodo

The first run of the updates utilised the central locking system to activate/de-activate the immobiliser,

i.e. ... unlock doors with fob ... doors unlock ... and PCM also gets a message to de-activate the immobiliser function of the PCM.

... by mid / late 98 the immobiliser was changed to the now typical, expensive ignition key transmitter and steering column receiver.

Well, when my immobiliser plays up (Nov 1997 XJ), my remote has no issues with locking/unlocking the doors, even the 'security' light on the dash will go out, however the immobiliser will still be active and cut out the engine after the 1-2 seconds of engine running...

[werd]

Originally Posted by carvesdodo

The first run of the updates utilised the central locking system to activate/de-activate the immobiliser,

i.e. ... unlock doors with fob ... doors unlock ... and PCM also gets a message to de-activate the immobiliser function of the PCM.

... by mid / late 98 the immobiliser was changed to the now typical, expensive ignition key transmitter and steering column receiver.

Is it as simple as that? If you replaced the central locking system with an after market kit then the immobiliser would still work (off and on)?

I'm not fixing it, I'm improving it!

[rustynuts]

Originally Posted by carvesdodo

The first run of the updates utilised the central locking system to activate/de-activate the immobiliser,

i.e. ... unlock doors with fob ... doors unlock ... and PCM also gets a message to de-activate the immobiliser function of the PCM.

... by mid / late 98 the immobiliser was changed to the now typical, expensive ignition key transmitter and steering column receiver.

Well said. I was wondering what all the fuss was about. It seems like a stop gap 97 issue. Thanks. Now I know.

[carvesdodo]

Originally Posted by Roler

Well, when my immobiliser plays up (Nov 1997 XJ), my remote has no issues with locking/unlocking the doors, even the 'security' light on the dash will go out, however the immobiliser will still be active and cut out the engine after the 1-2 seconds of engine running...

Sounds like your issue is either in the PCM ... or the wiring from the PCM to whatever, the PCM shuts down in the "immobilised" condition ?

Originally Posted by werd

Is it as simple as that? If you replaced the central locking system with an after market kit then the immobiliser would still work (off and on)?

I'm not fixing it, I'm improving it!

The immobiliser is a built in PCM function. Its on until something tells it to turn off.

Since it uses those damned CCD bus wires ... the twisted purple and white ones that link into most everything ... I dont know whether you can get an aftermarket one to operate it or not. ?

[carvesdodo]

Originally Posted by rustynuts

Well said. I was wondering what all the fuss was about. It seems like a stop gap 97 issue. Thanks. Now I know.

It seems it was a bodged up version,

... of the already, bodgey ZJ Grand Cherokee system ..

I figure the factory fitted chryco 8.25 diff is in the back of this model XJ, is an apology/consolation prize ... for the immobiliser ..

[werd]

Originally Posted by carvesdodo

The immobiliser is a built in PCM function. Its on until something tells it to turn off.

Since it uses those damned CCD bus wires ... the twisted purple and white ones that link into most everything ... I dont know whether you can get an aftermarket one to operate it or not. ?

It would be nice if it was just like a switch. Permanently closed/open, or even momentarily contact.
But then again, the door lock switch doesn't engage or disengage the immobiliser.
This requires further investigation.


I'm not fixing it, I'm improving it!

[Roler]

Where many have gone before....and never returned...
My kingdom for the person who has the fix for the dreadful 1997 immobiliser issue, I tell ye..